The SBBRKSM easichange kit replaces the discontinued BRK 660MBX optical and 670MBX ionisation smoke alarms and fits onto your existing BRK twist-fit alarm baseplate so there's no need for any DIY or an electrician. The kit consists of the replacement optical smoke alarm head with pre-connected easichange adaptor, an easichange removal tool, a quick change guide, and the full alarm manual. The SBBRKSM is a mains powered smoke alarm with a replaceable 9V alkaline backup battery like the 660MBX and 670MBX that it replaces. The optical sensor technology improves on the detection of slow smouldering fires and reduces the chances of false activations. Featuring a hardwire interlink allowing compatible easichange alarms to communicate with each other over the same wiring as your old BRK alarms, so that all will sound the alarm if one detects a fire.